This invention relates to reflectors for luminaire assemblies which are particularly suited for indoor lighting and certain architectural area and roadway lighting applications.
Suspended luminaire assemblies typically include, among other components, an optical assembly, an electrical assembly having a housing generally formed of metal for storing electrical components therein, a lamp, and a hanger member for suspending the assembly from its intended overhead location. Indoor suspended high-intensity discharge (HID) luminaires with open optics and high wattage lamps such as, for example, 400 W MH have traditionally used two kinds of optical units to direct light from the lamp onto the intended task: (1) transparent optical assemblies; and (2) opaque optical assemblies.
A typical transparent optical assembly is shown, for example, in FIG. 1 and designated generally by reference numeral 10. Assembly 10 consists of either glass or plastic 12, such that the distribution of light is ensured by a reflector, a refractor, or a combination of the two which can be achieved by known techniques such as, for example, prismatic structures.
As those skilled in the art will recognize, the desirable features offered by transparent optical assemblies such as that shown in FIG. 1 are high efficiency (generally greater than 90xc2x0), good light distribution, and the availability of a large uplight component. The uplight component for a glass reflector can be as high as 25% or greater of the total light emitted by the lamp. This typically includes approximately 10% coming from the top opening 14 of the reflector and approximately 15% coming through the glass 12. The fact that the glass reflector xe2x80x9cglowsxe2x80x9d produces a source of brightness that reduces contrast and is considered an optimal feature for many lighting tasks.
A typical opaque optical assembly is shown in FIG. 2 of the drawings and is designated generally by reference numeral 16. Assembly 16 consists typically of a spun or hydro-formed metallic dome 18 having an interior which has been polished and anodized or painted with a high reflectivity white finish. The desirable feature offered by opaque optical assemblies such as the assembly 16 of FIG. 2 is the cut-off produced by the dark reflector. This cut-off is specifically desirable for applications where brightness through the reflector 18 may interfere with the lighting task.
Cut-off in an opaque optical assembly is achieved at the expense of efficiency since the post-anodizing process yields a typical reflectivity of 85%. This results in luminaire efficiencies of no greater than 80%. Because the only uplight available through such as reflector 18 is from its top opening 20, the typical uplight component for metallic reflectors is generally on the order of 10%. Opaque assemblies and in particular metallic reflectors can, of course, be punched with perforations to vary the desired uplight. As those skilled in the art will recognize, metallic reflectors exist that have slots punched into them. Because of the metallic structure, however, the punching process must be performed prior to forming or it may tear during the spinning or hydro-forming process. Cost constraints also limit the amount of punching which can be performed subsequent to forming. Accordingly, the slots found in prior art opaque optical assemblies are generally few and large due to the constraints indicated above of the manufacturing processes. Such slots provide few large patches of uplight that are generally too bright and fail to produce ceiling uniformity.
Consequently, a need exists for a reflector which can produce efficiencies typical of glass reflectors yet having the cut-off typical of metallic reflectors. Such a reflector should also accommodate perforations as a means of varying the upright component as well as the overall appearance of the optical assembly.
In addition, certain high performance lighting such as architectural areas and roadway lighting utilize glass reflectors systems. A need exists for an architectural or roadway application reflector which can produce efficiencies typical of glass reflectors yet having the advantages of metallic reflectors. Such a reflector would provide uniform illumination with a high average as well a both a low maximum to minimum ratio and a low average to minimum ratio while still providing an aesthetically pleasing outer appearance.
It is a principal object of the present invention to provide an improved reflector having the efficiencies typical of glass reflectors with the cut-off typical of metallic reflectors.
It is a further object of the present invention to provide an improved reflector having a means to provide a varying amount of uplight without sacrificing cut-off.
It is still another object of the present invention to provide an improved reflector having a means for varying uplight typical of that provided by glass and plastic reflectors.
It is yet another object of the present invention to provide an improved reflector which can produce a radial distribution similar to that of typical HID reflectors.
Yet still further, it is an object of the present invention to provide an improved reflector which offers the ability to change its symmetry so as to efficiently produce biaxial distributions.
Still further, it is an object of the present invention to provide an improved reflector which can be manufactured with a low tooling investment for a large degree of design flexibility.
In carrying out these and other objects, features and advantages of the present invention, there is provided a faceted reflector for use in a suspended luminaire. The faceted reflector includes a plurality of reflector segments each having interlocking means for attachment to another segment. The plurality of segments when interlocked form the faceted reflector.
In a preferred embodiment, each of the reflector segments is comprised of pre-anodized and enhanced aluminum having a specular, semi-specular, or a diffuse finish. The segments have a substantially curved cross section in a vertical plane. When interlocked to form the faceted reflector, a dome-shaped optical unit is formed having a regular polygonal cross section in a horizontal plane. Still further, in the preferred embodiment, the interlocking means includes a plurality of tabs and slots for interlocking with respective slots and tabs of other segments.
In yet another embodiment, the faceted reflector includes a plurality of perforations in one or more of the reflector segments according to predetermined patterns so as to allow light to pass therethrough.
The above objects and other objects, features and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.